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Your asthma-suffering friends will not be affected by the smoke while
they are sitting in front of the fire or even just being in the room
because - and this is why open fireplaces are such a damn waste of
resources and are major polluters - all the air in the room is sucked
out thru the flue! The smoke ends up OUTSIDE the house. The open fire
also burns the oxygen in the room (and sucks it out outside) so you need
a way to replenish the burnt oxygen.

What heat you feel sitting in front of the fire is only radiant heat,
and this is only a small fraction of the total heat which is just blown
out thru the flue. One of the most inefficient ways of keeping warm.

My parents have an older place with an OFP and there's not much heat
that is lost thru the flue.
4-5 split chunks of redgum will heat the lounge / meals / kitchen (
it's a large open area ) for several hours.
The more modern stove types are even better. 4-5 chunks burn for hours
and would actually heat the room to an uncomfortable level.
Cheaper & arguably more efficient than burning non-renewable gas...